This is a case-control epidemiologic study of brain tumors occurring in children. Cases are those children (ages 1 day to 16 years) with a brain tumor who reside in the catchment area of eight 'cancer' registries included in the SEER program. Three controls are selected for each case by random digit dialing, matching for age, (plus or minus 3 years), sex and race. A one and one-half hour long questionnaire is administered to both parents by an interviewer in the parents' home. The questionnaire includes requests for information about demographic features, parents' exposure to possible teratogens and mutagens, familial history of tumor and birth defects, and exposure to infectious agents. During this project, questionnaires will be completed for approximately 400 cases and 1,200 controls. Data analyses for each morphologic subtype and site-specific tumor will be delayed until sufficiently many cases are available.